Breaking the interproximal contacts doesn’t need to be done with a skinny bur, some programs may hand you other burs instead of a needle bur, which is fine as long as your angulation is still upright. At the end the contact it must be open enough for a 016 diameter bur to freely pass, and it is possible to do that reduction with a larger bur from the get go. Here I’m using a 012, and the good thing of using a larger bur is that the margins are easier to get right from the beginning.
After breaking the contacts connect everything, go back and touch-up the functional cusp bevel and place a small bevel on the nonfunctional cusp too. Run your finger over the preparation and get rid of anything sharp. Don’t forget to check your occlusal clearance!
Step by Step
The occlusal, buccal and lingual portions of this lower first molar have been reduced already. To check and review these reductions, please follow the links below:
Provide LINKS for Occlusal Reduction, Buccal Reduction, and Lingual Reduction for Full Gold Crowns
Step 1: Practice First
Without running the handpiece, practice your angulation. Start from the buccal or lingual wall and go towards the proximal, taking note of your angulation.
Step 2: Interproximal Reduction
Video Demo (Mesial)
Video Demo (Distal)
Proceed with the reduction from the get go, you can make a sliver of enamel shell leaving in contact with the adjacent tooth just to have a little bit of a guard from the bur.
One technique, is to reduce the proximal surface starting from to occlusal and bringing it down slowly towards gingivally.
To check if you got a good clearance from the adjacent tooth, bring your bur interproximally near the gingiva and lift it up occlusally. If there is a catch, it means an enamel lip is present and you have NOT yet made a clearance.
Step 3: Making Interproximal Margins
Demo Video
On this point, you will see a triangular shaped enamel mound on the interproximal area, all you have to do is to even this out and combine the lingual and buccal margins into one continuous margin.
Bring your Chamfer bur and pass it through the interproximal. If it does not pass through, switch again to your needle bur (or a small chamfer bur) and enlarge the clearance a bit.
Then, use your Chamfer bur to connect the buccal and lingual margins to the interproximal margins. The margins should be continuous, even all throughout and smooth.
After everything is clear, we can now start finishing up everything.
LINK Hand Instrumentation and Refinement